The primary objective is to evaluate the improvement of antidepressant monotherapy on depressive and anxiety symptom in Chinese patients who meet Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) criteria for the comorbidity of major depressive disorder (MDD) and generalized anxiety disorder (GAD)

To evaluate the improvement of the quality of life of antidepressant monotherapy on Chinese patients who meet DSM-5 criteria for the comorbidity of MDD and GAD. To monitor adverse events (AEs) and serious adverse events (SAEs) of antidepressant monotherapy

Inclusion Criteria:

1. First episode outpatients in department of psychiatry, aged 18-65 years
2. Comorbidity of MDD and GAD according to DSM-5 criteria Hamilton Depression score (HAMD) of ≥18 at screening
3. HAMA≥14 at screening
4. Medically stable
5. Provision of written, informed consent.

Exclusion Criteria:

1. Suicide ideation
2. Use antidepressants within at least 14 days before study begin
3. Substance or alcohol dependence at enrolment (except dependence in full remission, and except for caffeine or nicotine dependence)
4. Opiates, amphetamine, barbiturate, cocaine, cannabis, or hallucinogen abuse within 4 weeks prior to enrolment
5. Unstable or inadequately treated medical illness (e.g. congestive heart failure, angina pectoris, hypertension, renal or hepatic dysfunction, cerebrovascular disease ) as judged by the investigator
6. Women in pregnancy or lactation
7. Medical conditions that would affect absorption, distribution, metabolism or excretion of study treatment.
8. Medical history with seizure disorder, except for febrile convulsion
9. Participation in another clinical study within 4 weeks (or longer time according to the local requirement)
10. Receive Electroconvulsive therapy (ECT) before study begin

Chinese patients who meet DSM-5 criteria for the combidity of MDD and GAD